Alan Pope gives a talk that introduces the concepts of wikis, how to use them and what their advantages are. This talk does not require any existing knowledge of the subject. See http://www.hantslug.org.uk/cgi-bin/wiki.pl?TechTalks for more details and copies of the presentation that accompanied the talk. This talk was given at the Hampshire Linux User Group (HantsLUG) meeting on 1st April 2006 at Southampton University.
There is an OGG Theora / Vorbis version available. The archive.org site doesn't seem to recognise Theora files at the moment. Get it here: http://www.archive.org/download/HampshireLinuxUserGroupWikisWhattheyareandhowtousethem/wiki20060401.ogg